1. Field of the Invention
The present invention relates to an electric double-layer capacitor, and more particularly, it relates to an electric double-layer capacitor having collectors prepared from conductive resin films.
2. Description of the Prior Art
Japanese Patent Laying-Open Nos. 163617/1986, 163618/1986, 163619/1986 and 163620/1986 disclose that an element for a conventional electric double-layer capacitor is formed by a gasket and collectors, which are sealed by a thermo-adhesion method. Each of the collectors is prepared from conductive film which is obtained by inflation molding or T-die extrusion molding of low-density polyethylene or high-density polyethylene which is provided with conductivity by a carbon material mainly composed of carbon black.
However, a collector prepared from low-density polyethylene easily obtains pinholes in the thermo-adhesion process. Further, when the collector is left for a long period of time, the electrolytic solution gradually infiltrates into the same to corrode metal parts in contact with the collector, in the worst case.
In a collector prepared from high-density polyethylene, on the other hand, the equivalent series resistance is greatly increased. Further, the conductive film of high-density polyethylene is fragile and easily broken, particularly since variations in the thickness of the components and that variations in applied pressure following storage in a case cannot be avoided.